1. Field of Invention
The present invention relates to an apparatus and method for marking at least two sides of a pellet-shaped article. In particular, the invention relates to an apparatus and method for marking both sides of a pellet-shaped article using a ramp-type conveyor system with at least one row of article receiving pockets.
2. Description of Related Art
A variety of devices have been developed for printing indicia on pellet-shaped articles using a conveyor system. Some of these devices are capable of simultaneously printing indicia on both sides of an article, while other devices are only capable of printing indicia on a single side of the articles.
For example, U.S. Pat. No. 4,189,996 to Ackley, Sr. et al. discloses an article carrying device (e.g. carrier) for printing indicia on both sides of a single row of articles. The carrier is specially designed to have a housing with two open sides so as to entrain the articles entirely therein. This configuration allows the sides of the articles to be exposed to printers placed on both sides of the carrier. That is, once the articles are entrained within the carrier, both sides of the articles face opposing printing devices. In order for printing to be accomplished, the carriers are positioned on the conveyor system and transported along a predetermined path past the opposing printers for simultaneously printing indicia on both sides of the articles.
However, in operation only one row of articles can be printed at a time using these carriers because the carriers are aligned in a single row on the conveyer so that the printers can be placed on opposing sides of the articles for printing. Also, when using these carriers, special article feed dispensers are needed to ensure that the articles are entirely entrained within the carriers. However, even when using the special article feed dispensers, the articles are not always dispensed properly into the carriers, thereby resulting in many carriers passing the printers without having articles entrained therein.
Other article carrying devices are designed so that indicia can be printed on a single side of the article. For example, U.S. Pat. No. 3,884,143 to Ackley discloses a tablet carrier link for precision printing. The link includes a supporting base connected to a conveyor. The link has a hollow body portion providing a space for an article. At least one side of the link is open for exposing a part of the article for printing. Like the Ackley Sr. patent, only one row of articles can be printed at a time using these links because the links are aligned in single fashion on the conveyor so that printing can be performed effectively.
By way of another example, U.S. Pat. No. 5,433,146 to Ackley discloses specially designed carrier bars for entraining articles. These carrier bars contain specially designed pockets so that articles can be substantially placed therein so that only one side of the article faces a printer. The carrier bars are fixed to a ramp-type conveyor system that transports the carrier bars along a predefined path and underneath a printer for printing indicia on the articles. Because the articles are placed within the pockets of the carrier bars, the sides of the articles are covered and indicia can only be printed on the top or one side of each of the articles.